An art teacher was sacked after a GCSE pupil stumbled upon explicit images when Googling an artist at a New Malden school, a tribunal has heard.

Peter Knowles, 54, also allegedly followed a Muslim student around a classroom at Coombe Boys’ School with a pair of scissors and began to “pretend he was cutting his beard” in autumn 2013. But the student was not interviewed by the school, the hearing was told.

A pupil was also left “very concerned” when Mr Knowles used the word ‘flange’ in a conversation with two students during a school detention, an employment tribunal in Croydon heard today.

Mr Knowles had chosen surrealist artist HR Giger for a GCSE class at the school, which led one student to use a school computer to research the artist and discover the “inappropriate” images.

Headteacher Deborah Walls made the decision to sack Mr Knowles after the allegations surfaced in autumn 2013.

Speaking to the tribunal, Mrs Walls said: “There were statements taken from the pupils and from staff and those were brought to my attention, all of which were concerning.

“I think there was care and concern towards [Mr Knowles] all the way through the process. It was a difficult time, it was very sensitive and we needed to ascertain what the situation was.

“I needed to make a decision that I felt was right for the school.”

Mr Knowles, who lives in Dorking, is suing the Coombe Secondary Schools Academy Trust for unfair dismissal and disability discrimination.

Representing himself in the tribunal, he argued that it is easy to access explicit material online and that he had done enough to safeguard pupils.

Mr Knowles was not at the school when the Year 12 pupil googled Giger and the class was being overseen by another teacher.

He told the court that when the allegations first surfaced Ms Walls told colleagues to “keep stum” and not to talk to him, even though staff acknowledged he was “really struggling”.

Regarding the Giger incident, he said: “I have to ask the question, ‘What more could I have done?’”

He added: “The accusation was that I had attempted to cut off the beard. It’s been reported so many different ways, this incident.”

But Ms Walls stood by her decision when questioned by Mr Knowles.

She said: “The name Giger was given to the art teacher. As a result of that a student did research the name of the artists and come across inappropriate images.

“You were aware that there were inappropriate images linked to Giger.

“Interviewing the [Muslim] student is something that could have been done.”

Regarding the use of the word ‘flange’, Ms Walls said she thought there were “inappropriate” double meanings.

HR Giger is most famous for his designs for sci-fi thriller Alien, but is also known for his sexually explicit paintings.

The tribunal continues.